I think part of the problem is it isn't set up as any sort of forced ranking or true 1-10 scale. When you actually rate a game, you choose between one and six "balls" in multiple categories. These are labeled as Terrible, Poor, Not So Good, Decent, Good, and Excellent. In order for someone to rate games low, they have to say that it is terrible or poor in multiple categories (depending on how they have their preference sliders setup). On the flip side, it's easy for a game to get rated higher than necessarily intended if you think it is excellent in multiple categories.
For example, my ratings show that I think AIQ is a perfect 10 and my top rated game. In actuality, I do not think it is either of those things. I do however think it is excellent in every rated category. But a perfect 10? Nope...I don't think any game is necessarily perfect. But in order for me to "sandbag" it down to the 8.5 or so that I would actually rate it at, I would have to lie and rate multiple categories as poor or "not so good", and I can't in clear conscious say that about anything on that game. I really do think every category deserves better than "good" on that game...and that defaults my rating to a perfect 10.
On the flip side take a game like Ghostbusters, which I think it one of the worst modern games. No, I have not rated it as I have not put enough time on one to give it a fair rating. But, if I were to rate it, there is no way I could rate every category honestly and have it be a 1 or even something like a 4. There is no way I could call the artwork, sound, or even the code or layout as being terrible or even poor. If I rated it there would be a couple not so goods, a few decents, and even a good and excellent or two. And that's a game I do not care for and if I had to force rank would be on the bottom of modern games.
The system just isn't set up to use the entire 1-10 scale if you are answering honestly. I'm not saying I know how to make it better, other than throw out ratings that are obvious trolls with an agenda. But even then...how do you define that, at least on the high side? Am I a "good troll"/ratings pumper because I rated AIQ a perfect 10? How do you mitigate that for people that are answering honestly?